Continuous Glucose Monitoring (CGM) has emerged as a critical tool in managing diabetes, particularly for assessing glycemic control through metrics such as Time-in-Range (TIR). TIR is defined as the percentage of time a person’s glucose levels remain within a target range, and it has been linked to better overall glycemic control, as indicated by lower HbA1c levels. This study, published in the Journal of Diabetes and Its Complications, explores the relationship between CGM wear-time and its impact on the TIR-HbA1c association in youth diagnosed with type 1 diabetes (T1D).
Background
The importance of maintaining a TIR greater than 70% has been established in previous research, correlating with improved HbA1c outcomes. However, the reliability of TIR data when CGM wear-time is less than optimal remains less understood. This study aims to fill that gap by examining how varying wear-times influence the correlation between TIR and HbA1c.
Methodology
The researchers conducted a study involving 60 youth with T1D, categorizing them based on their CGM wear-time into two groups: those with ≥70% wear-time and those with <70% wear-time. The study employed Pearson correlation coefficients to evaluate the relationship between TIR and HbA1c within each group. A Fisher r-to-z transformation was then used to compare the strength of these correlations.
Results
The findings revealed significant correlations between TIR and HbA1c in both wear-time groups. In the group with ≥70% wear-time, the correlation coefficient was r = -0.800 (p < .001), indicating a strong inverse relationship. Conversely, in the group with <70% wear-time, the correlation was weaker at r = -0.404 (p < .001). Notably, the difference in correlation strength between the two groups was statistically significant (z = 3.15, p = .0016).
Conclusion
The study concludes that while the association between TIR and HbA1c is weaker for those with less than 70% CGM wear-time, the statistical significance of the correlation suggests that lower wear-time data may still provide valuable insights when necessary. This finding highlights the potential utility of CGM data even when optimal wear-time is not achieved.
What this study does not show
This study does not establish a causal relationship between CGM wear-time and improvements in HbA1c, nor does it provide evidence for clinical outcomes based on the findings.
Evidence scorecard
- Analytic validity: Established
- Clinical validity: Established
- Clinical utility: Not established